1. Field of the Invention
The present invention relates to an inhibitor switch and to a positioning method and a positioning structure for mounting the inhibitor switch on an automatic transmission.
2. Description of the Related Art
A positioning method and a positioning structure for an inhibitor switch of the prior art are described in Unexamined Published Japanese Patent Application No. 8-74978 and shown in FIG. 9 and FIG. 10, for example. FIG. 9 is a perspective view showing the entirety of the inhibitor switch, and FIG. 10 is a sectional view showing the same.
As shown in FIG. 9 and FIG. 10, an inhibitor switch 101 is provided with a terminal block 103, a case 105 and a moving block 107. The terminal block 103 is equipped with a plurality of stationary terminals 109. The terminal block 103 is equipped with a positioning hole 113. The case 105 is bonded to the terminal block 103 by fusing it. The case 105 is equipped with slots 115 for fastening and fixing purposes.
The moving block 107 is equipped with moving contacts 111. The moving block 107 is rotatably supported by the terminal block 103 and the case 105. The moving block 107 is equipped with a fitting hole 121 to be fitted on a manual shaft 117 of the automatic transmission.
This inhibitor switch 101 is mounted by fitting the fitting hole 121 of the moving block 107 on the manual shaft 117 of the automatic transmission and by fastening the not-shown bolts inserted in the slots 115 to the housing side of the automatic transmission. At the time of mounting this inhibitor switch 101, an adjustment is made to align the detected position of the inhibitor switch 101 and a specific shift position according to the rotation of the manual shaft 117. This specific shift position is located, for example, at a neutral position (or N-position) of the automatic transmission.
For this adjustment, with the bolts to be fastened in the slots 115 being loosened, the entire inhibitor switch 101 is made rotatable within the range of the slots 115 with respect to the manual shaft 117. A hole 119a with a width across the flats of a positioning jig 119 is fitted on a fitting portion 117a with a width across the flats at the leading end of the manual shaft 117. Next, the entire inhibitor switch 111 is turned, and the positioning pin 119b of the positioning jig 119 is inserted into the positioning hole 113 of the terminal block 103. In this state, the bolts in the two slots 115 are fastened to fix the inhibitor switch 101 on the housing of the automatic transmission.
By the aforementioned fastening work using the positioning jig 119, therefore, the moving block 107 and the terminal block 103 are accurately adjusted to the N-position of the manual shaft 117, so that the inhibitor switch 101 can be reliably fixed in the accurately positioned state with respect to the manual shaft 117.
By the aforementioned positioning method and positioning structure of the inhibitor switch, however, during the stage in which the inhibitor switch 101 is assembled with the automatic transmission, the positioning adjustment has to be made by using the positioning jig 119, thereby causing the assembling work of the inhibitor switch 101 to increase in complexity.
An object of the present invention is to provide an inhibitor switch positioning method and structure, which can assemble an inhibitor switch in an accurately positioned state with an automatic transmission without any positioning adjustment.
According to one aspect of the invention, there is provided a positioning structure of an inhibitor switch including: a switch housing having a terminal block having stationary contacts and a cover; and a moving block fitted on a manual shaft of an automatic transmission and having a fitting hole and moving contacts for rotating with respect to the switch housing, wherein the inhibitor switch is fixed on the housing of the automatic transmission for detecting the shift position of the automatic transmission electrically from a rotational position corresponding to a relationship between the stationary contacts and the moving contacts in accordance with the rotation of the manual shaft of the automatic transmission. In the positioning structure, the switch housing and the moving block can be temporarily fastened by a tack-fastening member to be broken at a set torque, before the inhibitor switch is fixed on the automatic transmission, at corresponding rotation positions for detecting a specific shift position of the automatic transmission.
Therefore, it is possible to accurately position the corresponding rotation positions for detecting the specific shift position of the automatic transmission between the switch housing and the moving block.
After the moving block in this temporarily fastened state is fitted on the manual shaft at the specific shift position, the inhibitor switch can be fixed on the automatic transmission.
Therefore, it is possible to accurately position the specific shift position of the manual shaft and the corresponding rotation positions of the switch housing and the moving block for detecting the specific shift position. In this state, moreover, the inhibitor switch is fixed on the automatic transmission so that the positional relationship between the switch housing and the moving block and the manual shaft can be accurately determined.
After this, the temporarily fastened state can be released by rotating the manual shaft to break the easily broken portions.
Therefore, the inhibitor switch can be brought into a using state without any special work.
Thus, at the time of mounting the inhibitor switch, the inhibitor switch can be accurately assembled with extreme ease with the automatic transmission without any special positioning work using a jig.
According to another aspect of the invention, there is provided a positioning structure of an inhibitor switch including: a switch housing having a terminal block having stationary contacts; and a moving block fitted on a manual shaft of an automatic transmission and having a fitting hole and moving contacts for rotating with respect to the terminal block, wherein the inhibitor switch is fixed on the housing of the automatic transmission for detecting the shift position of the automatic transmission electrically from a rotational position corresponding to a relationship between the stationary contacts and the moving contacts in accordance with the rotation of the manual shaft of the automatic transmission. The terminal block and the moving block can be temporarily fastened by a tack-fastening member to be broken at a set torque, in advance before the inhibitor switch is fixed on the automatic transmission, at corresponding rotation positions for detecting a specific shift position of the automatic transmission and adapted to be broken at a set torque.
Therefore, it is possible to accurately position the corresponding rotation positions for detecting the specific shift position of the automatic transmission between the terminal block and the moving block.
After the moving block in this temporarily fastened state is fitted on the manual shaft at the specific shift position, the inhibitor switch can be fixed on the automatic transmission.
Therefore, it is possible to accurately position the specific shift position of the manual shaft and the corresponding rotation positions of the terminal block and the moving block for detecting the specific shift position. In this state, moreover, the inhibitor switch is fixed on the automatic transmission so that the positional relationship between the terminal block and the moving block and the manual shaft can be accurately determined.
After this, the temporarily fastened state can be released by rotating the manual shaft to break the easily broken portions.
Therefore, the inhibitor switch can be brought into a using state without any special work.
Thus, at the time of mounting the inhibitor switch, the inhibitor switch can be accurately assembled with extreme ease with the automatic transmission without any special positioning work using a jig.
In addition, according to still another aspect of the invention, the tack-fastening member is made of a resin and includes: a first fixed portion to be fixed on the side of the terminal block; a second fixed portion to be fixed on the side of the moving block; and an easily broken portion for connecting the first and second fixed portions. The corresponding rotation positions of the terminal block and the moving block can be temporarily fastened reliably by the tack-fastening member.
When the manual shaft is rotated after the assembly, moreover, the second fixed portion on the moving block side rotates with respect to the first fixed portion on the terminal block side so that the easily broken portion can be broken at the set torque. As a result, the inhibitor switch can be easily brought into the using state. Moreover, the first and second fixed portions and the easily broken portion can be integrally molded of resin with ease.
In addition, according to still another aspect of the invention, the first and second fixed portions are formed into a ring shape generally concentric to the fitting hole of the moving block, and the easily broken portion is provided in plurality in the circumferential directions between the first and second fixed portions. Therefore, the easily broken portions can be individually thinned and can be reliably broken at the set torque while suppressing their flexibility.
In addition, according to still another aspect of the invention, the first fixed portion is equipped with an outer press-fit portion, and the second fixed portion is equipped with an inner press-fit portion; the terminal block is equipped with an output press-fitting accommodating portion for press-fitting the output press-fit portion, and the moving block is equipped with an inner press-fitting accommodating portion for press-fitting the inner press-fit portion; and each of the press-fit portions has a crushing strength set higher than the strength of the easily broken portions. While the tack-fastening member is being reliably fixed by the press-fitting operation in the terminal block and the moving block, therefore, the easily broken portions can be reliably broken without inviting any looseness in the press-fits.
In addition, according to still another aspect of the invention, the terminal block is equipped with an inward circumference that abuts the outer circumference of the ring-shaped first fixed portion, and the moving block is equipped with an outward circumference that abuts the inner circumference of the ring-shaped second fixed portion, and an accommodating recess for accommodating the first and second fixed portions is formed between the inward circumference and the outward circumference. Therefore, the first and second fixed portions are accommodated in the accommodating recess so that the outer circumference of the first fixed portion abuts the inward circumference of the terminal block and so that the inner circumference of the second fixed portion abuts the outward circumference of the moving block.
When the easily broken portions are broken, therefore, the first fixed portion and the second fixed portion are to be deformed outward and inward, respectively. By the inward circumference and the outward circumference, however, the first and second fixed portions are supported and prevented from being deformed to transmit the breaking force reliably to the easily broken portions thereby to break them accurately at the set torque.
In addition, according to still another aspect of the invention, the first fixed portion is equipped separately of the outer press-fit portion with outer fastening portions to be fastened and fixed on the side of the terminal block, and the second fixed portion is equipped separately of the inner press-fit portion with inner fastening portions to be fastened and fixed on the side of the moving block, and the outer fastening portions are additionally thermally fastened and fixed on the side of the terminal block, and the inner fastening portions are additionally thermally fastened and fixed on the side of the moving block. Even after the easily broken portions were broken, therefore, the first fixed portion can be held on the terminal block, and the second fixed portion can be held on the moving block, so that the dust can be prevented from being accumulated.
Upon the outer press-fit portions and the inner press-fit portions, moreover, the thermal influences of the additional thermal fastening operations of the outer fastening portions and the inner fastening portions can be suppressed to suppress the looseness due to the thermal influences of the outer press-fit portions and the inner press-fit portions. Therefore, the easily broken portions can be reliably broken.
In addition, according to still another aspect of the invention, the outer press-fitting accommodating portions, the inner press-fitting accommodating portions and the accommodating recess are opened to the outer faces of the terminal block and the moving block. Therefore, the tack-fastening member can be easily mounted. Even if the tack-fastening member should come after being broken, moreover, it would go out of the inhibitor switch so that it would not trouble the function of the inhibitor switch.
In addition, according to still another of the invention, the easily broken portions are interposed in plurality at different spacings in the circumferential directions between the first and second fixed portions. When the inhibitor switch is used after the easily broken portions are broken, the intervals at which the individual broken faces of the easily broken portions of the first and second fixed portions simultaneously touch in the rotational direction when the second fixed portion is rotated with respect to the first fixed portion by the rotation of the moving block accompanying the rotation of the manual shaft are suppressed only one time for a rotation of 360 degrees. At the point just after being broken, even the broken faces of the easily broken portions of the first and second fixed portions contact each other and the states of simultaneous contact and no contact are not repeated so that the fluctuation of the operation torque can be drastically suppressed.
In addition, according to still another aspect of the invention, the easily broken portions are gradually thinned from both of the first fixed portion and the second fixed portion to the others to form stress-concentrated portions at their intermediate portions. When the second fixed portion rotates with respect to the first fixed portion, therefore, the shearing stress is concentrated at the stress concentrated portions of the easily broken portions to break the easily broken portions easily and reliably at the set torque at the stress concentrated portions. The broken faces of the easily broken portions can be easily extended along the directions of the corresponding rotations of the first and second fixed portions. When the second fixed portion rotates with respect to the first fixed portion, the broken faces at the easily broken portions of the first and second fixed portions can be suppressed from contacting to prevent the fluctuation of the operation torque more reliably.